Per The Fleet Type Submarine NavPers 16160, Chapter 7:
7A2. Engine induction. Air to the engine is supplied by natural induction through a 36-inch diameter ventilation stack and outboard valve in a compartment in the after end of the conning tower fairwater. The bottom of this stack has three branches, one 16-inch diameter branch for ship's supply and two 22-inch diameter branches, one port and one starboard. All the branches are located in the superstructure. The port pipe runs aft to a hull valve in the top of the inner shell, near the middle of the forward machinery compartment. The starboard pipe runs aft to a hull valve in the top of the inner shell near the middle of the after machinery compartment. These hull valves permit passage of air directly to their respective machinery compartments. Just forward of the after hull valve a 22 x 22 x 16-inch lateral bypass damper fitting is inserted in the induction pipe, the 16-inch outlet of which discharges into a 16-inch pipe, running aft to an auxiliary hull valve in the top of the inner shell in the maneuvering room, aft of the maneuvering control stand. This air, when thus bypassed, is for the purpose of creating lower temperatures in the vicinity of the control stand and eventually circulates forward again for consumption by the engines in the machinery compartments through the door or exhaust bulkhead valves in the forward maneuvering room bulkhead.
7A3. Ship's supply. During normal surface operation, ship's air is supplied through the combination engine induction and ship's supply outboard valve (Figure 7-1) located in the after end of the conning tower fairwater. A 16-inch diameter pipe in the superstructure runs from this stack to a hull valve in the top of the inner shell near the forward end of the forward machinery compartment. The 4000 cubic feet per minute ship's supply blower, which receives its air through this hull valve, attached fitting and inlet pipe, is just aft of the former and discharges into a splitter fitting directing air into both forward and after supply mains. This splitter fitting has a fixed damper that has been adjusted to divide the flow forward and aft in the right proportions. The supply mains run to the forward and after compartments of the vessel and are equipped with valves, branches, and louvers for adequate air distribution to all necessary spaces.
7A5. Ship's exhaust. The 2500-cubic feet per minute ship's exhaust blower is in the forward end of the forward machinery compartment and receives its air from a main, running forward to the after end of the forward torpedo room, having adequate valves, branches, and louvers from all necessary spaces forward of the forward machinery compartments. During normal surface operation, the discharge from the exhaust blower is directed into the forward machinery compartment through a damper-controlled louver in a fitting adjacent to the blower. When the ship is at the dock or laying to, with engines not running, this air, plus that discharged into all compartments aft of the crew's quarters by the ship's supply system, may find its way overboard via open hatches or engine induction hull valves, whichever may be most desirable under existing weather conditions. Any doors or exhaust bulkhead valves in the after bulkheads, necessary to permit natural egress of exhaust air from the boat by the above-mentioned means, should be left open. When the submarine is cruising on the surface, the discharge from the exhaust blowers is consumed by the engines. In this condition all airtight dampers in supply branches should be shut in both machinery compartments and maneuvering room. If air is being supplied to the after torpedo room, exhaust bulkhead valves must be left open in both forward and after maneuvering room bulkheads so that exhaust air may get back to machinery compartments for consumption by the engines.
7A6. Battery exhaust. Each of the two battery tanks normally receives its supply from the compartment above via two battery intakes, one near each end of the room. In an emergency, these may be closed off by gas-tight covers stowed near the intakes. In each battery tank, air is sucked through each cell by a network of hard rubber piping, eventually consolidating into one pipe connecting to a single fitting in the platform deck above the batteries. (See Figure 7-3.) To the top of this fitting is attached a riser, leading up to a damper fitting connected to the inlets of two battery exhaust blowers. Either or both blowers may be operated at any one time for each battery. The forward set is located in the overhead of the chief petty officers' quarters and the after set is overhead of the crew's mess room. Each pair of blowers discharges into its own common fitting, having a partial damper for flow regulation. These fittings discharge into the ship's exhaust main near the battery blowers.
During periods of battery exhaust, gases have high hydrogen content (see Section 7A7), a damper, normally left entirely or partly open to the inlet of the ship's supply blower, may be fully closed, thereby diverting all exhaust air (which contains battery gases) overboard through the normal ship's supply outboard piping system. In such a position, the damper uncovers a screened opening permitting inboard supply to the ship's supply blower from the forward machinery compartment.
An orifice plate is inserted in the battery exhaust riser from each battery compartment, and pressure fittings from each side of each orifice plate are piped to separate air flow meters in the maneuvering room. The type of meter used is an arrangement of differential pressure gage known as the Hays Air Flow Meter. An indication of the quantity of air flow indicators. Each of these indicators is provided by a scale marked in cubic feet per minute.
The operation of the battery ventilation system covering fan speeds, controller settings, and meter readings is detailed in the Bureau of Ships Manual, Chapters 88 and 62.
All piping and fittings in the superstructure are designed to resist sea pressure at the maximum depth of submergence.
Three conditions under which it may be necessary or desirable to recirculate the air inside the ship rather than take in air from the outside as described for normal operation are: a) when submerged, b) when using the air-conditioning coolers, and c) in case of damage to the outboard piping. When recirculation is taking place, all hull ventilation valves are shut. The ship's exhaust blower is discharging into the inlet of the ship's supply blower and the exhaust air from the after compartments of the ship is being picked up by the ship's supply blower. All this is accomplished by means of two damper-controlled louvers in a series of pipes and fittings between the discharge of the ship's exhaust and the inlet of the ship's supply blowers. To permit passage of exhaust air back to the forward machinery compartment, all bulkheads between the forward end of the after torpedo room and the machinery compartments must be open to the compartments surrounding them by means of open exhaust bulkhead valves or doors.
Two air-conditioning coolers for cooling and drying the air are installed in the supply lines; the larger forward one is located in the after end of the crew's quarters and the smaller after one is located in the forward end of the after machinery compartment. When the humidity in the vessel becomes excessive, the quantity of air passing through the cooler should be reduced in order that the temperature of the air that passes through the cooler may be lowered below the dewpoint and thereby increase the quantity of water extracted from the air. The coolers are provided with drains to collecting tanks or engine room bilges.
The supply and exhaust mains at the watertight bulkheads are attached to pressure-proof hoods surrounding lever-operated bulkhead valves on each side of the bulkhead. Each pair of valves is operated by the lever on either side of the bulkhead. No ship's exhaust main exists aft of the ship's exhaust blower, but provisions for allowing exhaust air in the after end of the ship to get back to the machinery compartments have been made. Each of the two watertight bulkheads at the two ends of the maneuvering room has a pair of light hoods surrounding lever-operated bulkhead valves on each side of the bulkhead. Each pair of valves is operated by the lever on either side of the bulkhead. Exhaust air may travel forward from the after to the forward machinery compartments only by means of the watertight door which must be left open for this purpose.
The ship's ventilation supply and engine induction valve, located in the after end of the conning tower fairwater, is operated hydraulically or by hand and is locked in either the open or shut positions by hand operation. The hand gear consists of a hand crank with two handles which operate a worm and worm gear so arranged as to raise and lower the valve stem through the hull by a bell crank and slotted lever arrangement. A double-acting piston type of hydraulic gear is in the power position. The hand gear also moves the hydraulic piston and can be used only when the control lever for engine induction on the flood control manifold is in the neutral position.
External gagging on the engine induction and ship's supply outboard valve is accomplished by a wrench-operated valve stem set flush with the deck. The valve stem is supported by a yoke superimposed on the valve body and is protected by a cover projecting slightly above the deck. Gagging of the engine induction and ship's supply outboard valve gags or position locks all internal operating gear. The operating gear for the engine induction and ship's supply outboard valve is fitted with a contact maker for the indicator lights in the control room, thus indicating the position (open or shut) of the valve.
There are four hull valves: one ship's supply, two engine induction, and one maneuvering room (auxiliary engine) induction. All four valves are of the flapper type and are gagged from the inside of the ship. All hull valves seat with pressure in the external piping
The operating gear for each of the following hull valves, one ship's supply, two engine induction, consists of an operating lever and a quick releasing gear located at a suitable distance from the valve and connected to it by means of intermediate levers and connecting rods. For opening each valve, the operating lever must be used, and may be used for closing to ease the valve to its seat after tripping. However, the valve can be shut in an emergency by squeezing the handles, thus tripping the quick-releasing mechanism which permits the valve to seat by its own weight.
The operating gear for each hull valve is fitted with a contact maker for indicator lights in the control room and engine rooms to show open and shut positions.
